Desalination Using Positively Buoyant Or Negatively Buoyant/assisted Buoyancy Hydrate - Patent 6733667

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Desalination Using Positively Buoyant Or Negatively Buoyant/assisted Buoyancy Hydrate - Patent 6733667 Powered By Docstoc
Description: In general, the invention relates to desalination or other purification of water using gas or liquid hydrates to extract fresh water from saline or polluted water. In particular, the invention relates to desalination or purification of saline orpolluted water using methodologies which are virtually self-sustaining and which produce a cold water output that is suitable for refrigeration. The methodologies may be practiced in land-based installations or, in some cases, on mobile platforms.BACKGROUND OF THE INVENTIONIn general, desalination and purification of saline or polluted water using buoyant gas hydrates is known in the art. See, for example, U.S. Pat. No. 5,873,262 and accepted South African Patent Application No. 98/5681, the disclosures of whichare incorporated by reference. According to this approach to water desalination or purification, a gas or mixture of gases which spontaneously forms buoyant gas hydrate when mixed with water at sufficiently high depth-induced pressures and/orsufficiently low temperatures is mixed with water to be treated at the relatively deep base of a treatment column. According to prior technology, the treatment column is located at sea. Because the hydrate is positively buoyant, it rises though thecolumn into warmer water and lower pressures. As the hydrate rises, it becomes unstable and disassociates into pure water and the positively buoyant hydrate-forming gas or gas mixture. The purified water is then extracted and the gas is processed andreused for subsequent cycles of hydrate formation. Suitable gases include, among others, methane, ethane, propane, butane, and mixtures thereof.The previously known methods of desalination or purification using buoyant gas hydrates rely on the naturally high pressures and naturally low temperatures that are found at open ocean depths below 450 to 500 meters when using pure methane, orsomewhat shallower when using mixed gases to enlarge the hydrate stability "envelope," and the desal